From /usr/local/bin/secpanel:

    set mintcl 8.0
    set mintk 8.0

    if {[info tclversion]<$mintcl || $tk_version<$mintk} {
		puts -nonewline stderr "For running secpanel:\nTcl $mintcl/Tk $mintk minimum versions required. "
		puts stderr "You have Tcl [info tclversion]/Tk $tk_version"
		exit 1
    }